Fixes for return statement, make Evaluate function on script return value

tests/integration/Tables.cpp

@@ -34,11 +34,10 @@ TEST_CASE( "Index string table", "[integration]" ) {
     Script* script = Script::Create(
             R"(
 table = {'bla', 'test', 'foo', 'bar'}
-result = table[3]
+return table[3]
 )");
     REQUIRE(!script->Diagnostics -> HasErrors());
-    script->Evaluate();
-    auto variable = script->GetVariable("result");
+    auto variable = script->Evaluate();
     REQUIRE(variable != nullptr);
     REQUIRE(*variable->EvaluateString() == "foo");
     delete script;
@@ -71,11 +70,10 @@ table = {
         return foo
     end
 }
-result = table["getFoo"]()
+return table["getFoo"]()
 )");
     REQUIRE(!script->Diagnostics -> HasErrors());
-    script->Evaluate();
-    auto variable = script->GetVariable("result");
+    auto variable = script->Evaluate();
     REQUIRE(variable != nullptr);
     delete script;
 }